Notes

The damage done by poison might be based on total HP, poison resistance or something else. (needs confirmation)

Against various enemies it resulted in 12, 13, 14 or 15 HP drained each second.

The daggers can briefly stagger most smaller enemies, making it easier to keep throwing them until the target is poisoned. Relatively effective on NPC hunters (mostly on the Cainhurst Hunter at the end of Eileen's questline).

my thoughts, what is the items poison add, gems add a specific amount of poison, so how much poison add do the poison knives deal per hit, does it scale, vary by enemy type or does every enemy have they're set resistance to the poison knives?

They actually do some damage but are useless against actual players in pvp. If they have an antidote which is really common, landing 3 hits with a knife is really not worth the risk for dealing another 5 damage with poison. Use them on NPC hunters instead they absolutely make the toughest fights a breeze

how did people find out the prices for these before beating rom/entering cathedral ward? to GET the eye watcher badge you need to get to Yahar'Gul, which is acessible after beating rom only (I don't mean the Hypogeum Gaol, you cant get upper cathedral ward key there).